Salts dissolved in freshwater sources, measured as water hardness or total dissolved solids (TDS), can create problems in industrial, commercial, and residential uses of water, and processes to remove these salts have long been practiced. As human freshwater use intensifies, our water sources are becoming increasingly saline due to a variety of causes: agricultural runoff; urban runoff containing road salt; over-pumping of groundwater leading to intrusion of seawater into aquifers; and exploitation of brackish water sources not previously considered for human use. Thus, the demand for TDS reduction is expected to increase into the future, and new technologies will be required to improve the efficiency and environmental sustainability of TDS reduction processes.
Water purification devices used to remove such salts include ion reduction devices such as deionization systems, continuous or batch-wise, and reverse-osmosis systems. The compartments of such devices used to collect or concentrate salt ions must be cleaned, flushed, and/or maintained on a regular basis to avoid fouling and scale build-up. Often, acids and/or acid water are used for such steps. Supply of acids and/or acid water can be costly, particularly when large beds of resin are used such that resin requires off-site regeneration and/or use of strong acids. There is an ongoing need to improve the way devices that collect or concentration salt ions are cleaned, flushed, and/or maintained.